93 4runner brake light problems

My money is on a defective light bulb.

The bulbs have two filiments, one for the running lights, and the other for the brake lights. You need new bulbs. Back in the olden days when Detroit reigned king, this bulb was always an 1157. With the advent of Japanese and German cars, the bulb number may have changed. No matter what you need, if you take the cover off and remove the bulb, you will find a number stamped on the base. Buy more bulbs with the same number.

PS Sometimes the bulbs can be easily unscrewed from the back of the lamp assembly. I do not know if your 4Runner has this feature, or if you have to take off a couple of screws to get to the light bulbs.

I already changed the bulb a few times, and even swapped it with the other side. I still have the same problem.

If you swapped bulbs, and the problem remained the same, then the socket itself is not grounded well. If the problem moves where the bulb moves to, then the bulb is the trouble, but if the problem stays put as the bulbs move around, then the truck is the problem. Start by making sure the ground connections are good, then start chasing down the voltage.

The bulb is grounded by the outside case, and the voltage is applied through the nipple(s) on the bottom. The socket of the bulb is connected to the case, that is connected via a mounting screw to the body. I suspect the mounting screw is the problem. Polish the screw and the metal tab that it secures to ...

Let us know if that fixes your problem.

Could be a bad ground wire or a loose or broken power wire. Invest in an inexpensive VOM (volt-ohm meter) at your local hardware store and check for voltage at the socket. If you have voltage there then you can just clean-up the connections or ground wire. If you have no voltage at the socket then it's time to start tracing wires to find the loose connection or broken wire.

My schematic (such as it is) says the brake light ground wire (seperate wire and not just grounded to the socket/body) is "white with a black stripe." The power wire is shown as "green with a white stripe."

Good luck and like Jeff said, let us know what happens, good or bad.

dennis in nca

Also be sure to check harness plug connector under the bumper. It's where trailer connectors hook in. Could be a bad ground or loose pin connector. If you have a trailer plug check that for a short also.

Alright, I finally got a friend here tonight to look at the problem. We narrowed it down to 2 possibilities.

First thing we cut off the trailer harness completly. We weren't getting a good reading from it, and I'm not using it anyway (I still havn't reinstalled the trailer hitch).

Second thing I seem to have a problem with with a faulty light socket. For some reason, while playing with it, it would stop working for no apparent reason.

So tomorrow, I'm gonna go get a new light socket and we'll be replacing that soon.

Thanks all for the help, and if anything else needs to be done, I'll make sure to keep you posted.

Thats what fixed the backup light problem in my 82 pickup, new sockets. The old ones were wore down so the bulb would only shine when put in at and angle.